The present invention relates to a disc chipper for use in chipping wood for subsequent pulping. More particularly the invention relates to a disc or tool wheel which is mounted for rotation about an axis in the disc chipper.
The disc or tool wheel includes a working face and an opposing discharge face. A plurality of knives or chipper tools are mounted to the working face to create the wood chips. A corresponding plurality of chip outlets extend through the tool wheel to discharge the chips produced in the chipping process. Each chip outlet is an elongated aperture, having a length which is at least equal to that of the tool. The chip outlet defines a longitudinal axis, which is typically arranged in the radial direction or at a slightly offset angle relative to the radial direction.
Generally in tool wheels, the ends and side surfaces of the chip outlets are perpendicular to the face of the disc. The outlet or aperture present in the basic material of a tool wheel may become worn so that it is no longer perpendicular relative to the face of the wheel or disc. This is typically rectified by means of a separate attachment fitted to the end of the chip outlet.
In a prior known arrangement, the perpendicular end of a chip outlet is fitted with an attachment which provides the end of the chip outlet with a beveled guide for securing a greater flow of chips produced in the chipping process through the chip outlet. Such an attachment reduces significantly the exploitable length of a chip outlet and its associated chipping tool. Further, these attachments are difficult and expensive to manufacture and maintain, thus incurring continuously high costs as such attachments must be replaced as a result of wear and tear.